1. Field of the Invention
The present invention relates to scroll compressors that may compress a fluid (e.g. a refrigerant gas) by utilizing stationary and movable scrolls and may discharge the compressed fluid via a discharge valve. The present invention particularly relates to scroll compressors that have a compact inner structure and that are utilized in vehicle air conditioning systems.
2. Description of the Related Art
A known scroll compressor is disclosed in the Japanese Laid-open Patent Publication No. H11-2194, which scroll compressor includes a drive shaft, a drive shaft member including a crank shaft coupled to the drive shaft, a stationary scroll and a movable scroll coupled to the crank shaft. A compression chamber is defined by a space between the stationary scroll and the movable scroll. When the drive shaft rotates, the drive shaft member rotates together with the drive shaft and, at the same time, the drive shaft member orbits or revolves around a rotational axis. The revolution or orbital movement of the drive shaft member is transmitted to the movable scroll by means of a bearing member provided between the drive shaft member and the movable scroll. When the movable scroll orbits with respect to the stationary scroll, the volume of the compression chamber is reduced and thus, the fluid drawn into the compression chamber is compressed and discharged from the discharge port. The discharge port is defined within the movable scroll in accordance with the compression chamber in its minimum volume. The discharge port is opened and closed by means of a discharge valve. When the discharge valve closes the discharge port, backflow of the compressed fluid to the compression chamber can be prevented. On the other hand, when the discharge valve opens the discharge port, the compressed fluid can be discharged from the discharge port.
In order to reduce energy loss during operation of the scroll compressor, it is necessary to reduce heat generation caused by the crank shaft frictionally contacting the bearing member. Thus, in order to reduce such heat generation, the surface areas of the crank shaft and the bearing member have been reduced by reducing the diameters of the crank shaft and the bearing member. However, the portion of the movable scroll that includes the discharge valve consequently will also be reduced when the diameters of the crank shaft and the bearing member are reduced. As a result, the discharge valve also must be reduced in size, thereby limiting design options for the discharge valve.
It is, therefore, an object of the invention to provide improved scroll compressors that can reduce energy loss due to heat generation caused by frictional contact between the rotating portions of the scroll compressor, while still providing sufficient area to install a discharge valve.
In scroll compressors according to the present teachings, a crank shaft is coupled to a movable scroll and the movable scroll revolves or orbits via a bearing member. Further, a spacer may be disposed between a boss of the movable scroll and the bearing member.
According to the present teachings, because the spacer is provided between the boss and the bearing member, the diameter of the bearing member can be reduced, while not reducing the diameter of the boss. That is, movable scroll can have a sufficient area to mount a discharge valve and therefore, it is not necessary to reduce the dimension of a discharge valve. On the other hand, heat generation due to frictional contact between the boss and the bearing member can be reduced, because the diameter of the bearing member and the diameter of the crank shaft can be reduced by means of the spacer. Therefore, a compact space design of the scroll compressors can be realized.
Other objects, features and advantage of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.